1. Field of the Invention
The invention relates to methods of doping a semiconductor layer on a substrate.
2. Prior Art
A variety of methods for doping a semiconductor element with a doping material are known. In one such method, a dopant is diffused into the semiconductor element from a gaseous phase by the use of a heat treatment. For example, a mixture of a gaseous dopant or a gaseous compound which yields the desired dopant, a carrier gas, such as a rare gas and a suitable gaseous semiconductor compound, such as silane, are brought into contact with a heated substrate so that a doped semiconductor layer is pyrolytically deposited on the substrate. In another known method for doping a semiconductor element, an insulating layer such as a SiO.sub.2 -layer having a dopant substance therein is applied onto a semiconductor element which is to be doped. During the subsequent heat treatment of such an arrangement, the dopant atoms diffuse from the insulating layer into the semiconductor layer so as to form a doped semiconductor layer. In yet another known doping method, suitable dopant ions are introduced into a semiconductor element via an applied electrical field, i.e. by ion implantation.
All of such known methods have certain advantages and depending on the type of doping required, one such method may be chosen to provide the desired results. However, the ever-increasing requirement for semiconductor components, particularly composed of silicon, require an improved method for doping wherein an extremely uniform dopant distribution in the semiconductor element can be simply and reliably achieved.